ML19350C442
| ML19350C442 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 02/25/1981 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| IAL-81-12, NUDOCS 8104010732 | |
| Download: ML19350C442 (2) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION O
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631 PARK AVENUE
% * *...,o#g KING OF PRUSSIA. PENNSYLVANIA 19406 Docket No. 50-423 FEB 2 51981
,3 Q g File No. IAL 81-12
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fikB Northeast Nuclear Energy Company c':/
y ATTN: Mr. W. G. Counsil if o,4,Jf,I4 U bi 3
% g7987A 'g Senior Vice President - Nuclear 4
Engineering and Operations "v,1
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P. O. Box 270 4
Hartford, Connecticut 06101
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f Gentlemen:
Subject:
Design Analysis, Substitution of Grade 60 Rebar for Grade 40 Rebar This refers to the meeting held on February 18, 1981 at the Northeast Utilities Service Company (NUSCO) corporate office in Berlin, Connecticut with representatives of NRC, NUSCO, and Stone and Webster Engineering Company (S&W) to discuss the Millstone 3 structural design change of substitution of Grade 60 rebar for the original design specified Grade 40 rebar.
Attendees at this meeting were:
S. D. Ebneter, NRC - Region I S. K. Chaudhary, NRC - Region I E. J. Gallagher, NRC - IE:HQ L. C. Albee, NUSCO W. R. Rotherforth, NUSCO B. J. Kiley, S&W J. P. Allen, S&W D. f. King, S&W Based on this meeting, it is our understanding that the following steps have been or will be accomplished:
1.
Flexural members approximating 75% of the ratio of tension reinforcement which corresponds to balanced condition per ACI-318-71 in original design will be identified in those Category I structures affected by the rebar substitution design change.
Those structures, slabs and walls, that are scheduled for concrete placement in the succeeding two month period will be documented in a matrix to be transmitted to Region I on or before February 24, 1981.
2.
Flexure members will be analyzed for conformance to the limitation of rebar to 75% of balanced ratio as specified in ACI-318-71, Section 10.3 for design conditions of Grade 60 rebar.
The balance ratio is to be determined quantitatively by the formulae and methods outlined in ACI-318-71, Section 10.3.
19104 0 7 @ M A
Northeast Nuclear Energy Company 2
The specific methodology of analysis will be transmitted to Region I for review and concurrence on or before February 24, 1981.
3.
As per your memorandum FM-MP3-2242, a hold on the placement of concrete in affected structures will remain in effect until the required analyses are performed per the methodology concurred in by Region I.
In the event that a generic analysis is deemed applicable, the rationale shall be documented as part of the analysis. The completed analyses and conclusions shall be submitted to Region I for review and concurrence before the hold on concrete placement is lifted.
Rebar installation can continue but in no case shall construction processes proceed beyond an irreversible point.
4.
The analyses of affected in place structures will be performed to determine conformance with ACI-318-71 per item 2 of this letter.
The licensee will establish a schedule for these analyses.
5.
The licensee will prepare a final summary report of the analyres of affected structures, with a delineation of design inputs and conclusicas in relation to the structures conformance with the requirements of ACI-?l8-71, as a final response to the potential 10 CFR 50.55(e) report of Fearuary 5, 1981.
If our understanding of your implemented and planned action is not in accordance with the actual steps implemented or planned, please contact this office by telephone and in writing within.24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Sincerely, W
e.
W Boy e H. Grier Director cc:
K. W. Gray, Construction Quality Assurance Lead H. R. Nims, Director of Nuclear Projects S. R. Toth, System Superintendent Generation Construction J. F. Opeka, Station Superintendent J. R. Himmelwright, Licensing Safeguards Engineer D. G. Diedrick, Manager of Quality Assurance
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